Process of making dialkyl barbituric acid.



UNITED STATES Patented May 16, 1905.

PATENT OFFICE.

MAX ENGELMANN, OF ELBERFELD, GERMANY, ASSIGNOR TO FARBEN- FABRIKEN OF ELBERFELD 00., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PROCESS OF MAKING DIALKYL BARBITURIC ACID- SPEGIFIGATION forming part of Letters Patent No. 789,902, dated May 16, 1905.

Application filed February 28, 1905. Serial No. 247,778.

NHCO R NHOO (R meaning an alkyl radical) which bodies possess valuable therapeutic, especially soporific, properties. The process for the preparation of these compounds consists in first condensing dialkyl malonyldiamid of the gen- 2 5 eral formula:

(JO-.NHz R R l 3 OONH2 with neutral carbonic esterssuch as dimethyl carbonic ester, diethyl carbonic ester, methylethyl carbonic ester, diphenyl carbonic ester, or the like'by means of alkaline condensing agents, and, secondly. isolating the resulting dialkyl trioxypyrimidins (dialkyl barbituric acids) from the reaction mixture.

In order to carry out my process practically, I can, for instance, proceed as follows:

Example 1: Forty-six parts of sodium are dissolved in eight hundred parts of alcohol, and the solution thus obtained is mixed with one hundred and eighteen parts of the diethyllc ester of carbonic acid and with one hundred and fifty-eight parts of diethylmalonyldiamid. It is heated for four hours in an autoclave at 120 centigrade. The reaction takes place according to the following equation:

After cooling the sodium salt of the diethyl trioxypyrimidin is filtered 0H and decomposed by means of dilute acetic acid. By a recrystallization from hot water the free body is obtained in the shape of crystals.

Example 2: One hundred and forty parts of dimethylmalonyldiamid and two hundred and ten parts of diphenyl carbonic ester are added to a solution of forty-six parts of sodium in eight hundred parts of alcohol, and the resulting mixture is heated in an autoclave at 120 centigrade for four hours. After cooling dimethyl barbituric acid is isolated and purified by a recrystallization from water.

Example 3: Amixture of one hundred and eighteen parts of diethyl carbonic ester, one hundred and thirty parts of diethylmalonyldiamid, and one hundred and forty parts of solid sodium ethylate is heated at 120 centigrade for from four to five hours. After cooling the reaction mass .is mixed with Water and acid ulated, by which means the diethyl barbituric acid is precipitated. It is filtered off and recrystallized from water.

Example 4: Forty-six parts of sodium are slowly introduced into a mixture of one hundred and fifty parts of diethyl carbonic ester with one hundred and sixty parts of diethylmalonyldiamid. A violent reaction ensues. After it has ceased the mass is heated for some time at MO centigrade. It is dissolved in water, and from the resulting solution the diethyl barbituric acid is precipitated by acidulation. It is filtered off and purified by crystallization.

Example 5: A mixture of two hundred and twenty parts of diphenylcarbonic ester, one hundred and ninety parts of dipropylmalonyldiamid, and one thousand parts ofsodium amid is heated at 14:0 centigrade in an oilbath for from three to four hours. After cooling the melt is dissolved in water and the resulting dipropyl barbituric acid is precipitated by acidulation. It is filtered off and recrystallized from water.

The process proceeds in an analogous manner for the production of the other dialkyl barbituric acids.

7 Having now described my invention and in what manner the same is to be performed, What I claim as new, and desire to secure by Letters Patent, is-

1. The process for the production of dialkyl barbituric acids having the above-given general'formula, which process consists in first condensing dialkylmalonyldiamid with neutral carbonic esters by means of alkaline condensing agents and secondly isolating the resulting 5-dialkyl-24.6-trioXypyrimidins, substantially as hereinbefore described.

2. The process for the production of diethyl barbituric acid, which process consists in first condensing diethylmalonyldiamid with neutral carbonic esters by means of alkaline condensing agents and secondly isolating the resulting 5 diethyl 2. 4. 6 trioXypyrimidin, substantially as hereinbefore described.

3. The process for the production of diethyl barbituric acid, which process consists in first condensing diethylmalonyldiamid with neutral carbonic esters by means of alkaline alcoholates and secondly isolating the resulting 5 diethyl 2.4. 6 trioxypyrimidin, substantially as hereinbefore described.

4. The process for the production of diethyl barbituric acid, which process consists in first condensing diethylmalonyldiamid with diethyl carbonic ester by means of sodium ethylate and secondly isolating the resulting 5 diethyl 2.4.6 trioxypyrirnidin, substantially as hereinbefore described.

In testimony whereof I have signed my name in the presence of two subscribing witnesses.

MAX ENGELMANN. l/Vitnesses:

OTTO KoNIe, PAUL HODEIGE. 

